Weekend Adventures – Capitola Fossils

On the way back from camping in Monterey last weekend, some friends and I decided to stop by Capitola Beach, in the small beach town of Capitola, California (just east of Santa Cruz). We last visited Capitola in 2005.

It’s a popular destination for tourists and beginning surfers, but it’s also an excellent spot for those interested in collecting Pliocene aged marine fossils that range from common mollusks to seal bones and even whale bones. The best time to visit the beach is at low tide, when the bedrock outcrops usually hidden by surf are accessible. Because of the constant erosion of the cliffs around Capitola, each visit is a new experience in terms of what you will findsee.

Here Pliocene Purisima Formation, described by Cummings et al., (1962) as abuff-yellow to light brown and gray, fine-grained sandstone and siltstone, can be seenhere eroding away. This formation has been dated at 3 -1 Ma. At this locality, thePurisima Formation contains numerous dense layers of fossilized mollusk coquinas,ranging from 3-20 cm in thickness. These are interbedded with thin to thickargillitic sandstone beds and thin phosphatic silt and mudstone beds. The alternating fineto coarse-grained bedding is believed to reflect transgressive and regressive periodsassociated with uplift due to wrench tectonics and sea level changes (Clark et al., 1979).Faulting within the formation can be recognized based upon the existence of slickensidespreserved in some of the fractures

Also, here is a fantastic photo gallery by Paul Slocombe and taken in 2007 featuring many different types of Capitola fossils.